1. Field of the Invention
This invention relates generally to integrated circuit packages to accommodate one or more light sources, and more particularly, to integrated circuit packages having light coupling inputs.
2. Description of the Prior Art
A great deal of inventive effort has been devoted to the generation of electrical impulses from specialized light sources and to the elimination of the effects of ambient light with modulators, collimeters, lense systems, selective filters, etc.
A more recent field of interest in the opto-electronics technology concerns the transmission of light through specially designed optical glass fibers and/or through plastic light pipes which act as wave guides or light guides and to the generation and recovery of optical signals therefrom.
Prior art which is related to the opto-electronic technology and may also be related to this disclosure is cited as follows:
U.S. Pat. No. 3,982,123 issued Sept. 21, 1976 to J. E. Goell et al., discloses a variety of arrangements for tapping off a portion of the light signal from an optical fiber wave guide without requiring that the fiber be terminated or cut. This is done with a grooved or slotted clear plastic coupling body (which body also contains a photodetector) whose index of refraction is equal to or greater than the usual cladding material that is used on each fiber optic element. This patent deals exclusively with taking a signal off of an optical fiber without terminating or cutting the fiber, but does not remove a signal from a terminated light pipe and does not disclose an IC type package.
U.S. Pat. No. 3,977,762 issued Aug. 31, 1976 to C. P. Sandbak, describes an optical coupler consisting of a linear array of optical wave guides arranged to direct information from a document to a photosensor module. A plurality of optical wave guides are spaced along the document and compressed adjacent to the photosensor array. This patent describes a special purpose optical coupler with a plurality of inputs and outputs based on glass fiber optic technology, but no IC type package is disclosed.
U.S. Pat. No. 3,968,564 issued July 13, 1976 to A. J. Springthorpe, describes a method of accurately aligning a fiber optic wave guide with a light emitting diode by etching a clearance hole in a substrate centered over the diode. This patent does not disclose an integrated circuit package with optical input means.
U.S. Pat. No. 3,948,582 issued Apr. 6, 1976 to D. J. Martin describes an optical fiber connector set consisting of a plug whereby the male connector element is the end of an optical fiber wave guide and the female connector element consists of a conical plastic socket terminated with a fiber optic section. The mating plug and socket is either bayonet connected or threaded together with a freely rotatable outer sleeve. When the plug and socket of this prior art patent are mated, the two fiber glass ends are in contact or are very closely spaced apart. U.S. Pat. No. 3,948,582 also includes a double female adaptor for joining two fiber optic wave guide sections which are quipped with plugs. While U.S. Pat. No. 3,948,582 includes a cavity designated for a light emitter or detector in the female receptical, this prior art patent concerns mechanical details of a plug, socket, and adaptor and does not disclose an integrated circuit package or optical coupler.
U.S. Pat. No. 3,944,328 issued Mar. 16, 1976 to A. H. Kent et al., describes a device for in-line coupling of two lengths of optical wave guide elements. Also a subject of this patent is a method of casting a suitably dimensioned coupling block from a two-part epoxy. The fiber optic ends are fastened in the coupler with a high refractivity transparent cement. There is no disclosure or teaching in this patent of an integrated circuit package with an optical input coupler.
U.S. Pat. No. 3,757,127 issued Sept. 4, 1973 to Vir A. Dhaka, describes a photodetector assembly consisting of a square photodetector array with a plurality of photo-responsive elements coupled to fiber optic wave guides. The photodetector assembly is mounted in a square apertured retainer to facilitate attachment to a formed and cemented bundle of fiber optics so each fiber optic wave guide is coupled to a photo element on a one to one basis. Thus, the luminous information on each fiber optic is converted to a separate electrical signal. This patent does not disclose an integrated circuit package.
U.S. Pat. No. 3,423,594 issued Jan. 21, 1969 to A. G. Galopin, describes a photosensitive semiconductor device in which a plurality of fiber optic light rods are coupled to a light sensitive base portion of what is essentially a phototransistor. Combinations of light signals on the fiber optics and design features of the phototransistor will permit several varieties of logic mixing, modulation, demodulation, and integration functions to be performed. Progressive energization of the fiber optics inputs will produce step functions in the output circuit. This patent combines the inputs of a plurality of fiber optics into a single output signal. However, this prior art patent does not disclose an integrated circuit package.
U.S. Pat. No. 2,640,901 issued June 2, 1953 to T. H. Kinman, describes the use of discrete semiconductor devices, namely, a point contact germanium diode and a point contact germanium transistor which function as photoelectric devices by the addition of an acrylic or quartz light pipe arranged to illuminate the germanium device in the vicinity of the point contact. This patent also does not disclose an integrated circuit package.
The prior art described above is only a few of many patents that have been issued relating to opto-electronic semiconductor devices. However, none of the cited prior art is directed to the problem of coupling light into an IC package which includes a photo-responsive device. Furthermore, none of this prior art is directed to the problem of efficiently coupling light into an IC package while still permitting the semiconductor chip in the package to be properly protected by a suitable encapsulating material.
Accordingly, a need existed for a simple, cost effective, technique of providing an optical input to an integrated circuit package.